How to get an IP address from network interfaces

[dangbinghoo]

On Thursday, 21 April 2022 at 07:38:04 UTC, Alexander Zhirov 
wrote:
> On Thursday, 21 April 2022 at 07:20:30 UTC, dangbinghoo wrote:
>> On Thursday, 21 April 2022 at 07:04:18 UTC, Alexander Zhirov 
>> wrote:
>>> I want to get the IP address of the network interface. There 
>>> is both a wireless interface and a wired one. Is it possible, 
>>> knowing the name of the network interface, to get its IP 
>>> address?
>>
>> ```d
>> 	import core.sys.posix.sys.ioctl;
>> 	import core.sys.posix.arpa.inet;
>> 	
>> 	import core.stdc.string;
>> 	import core.stdc.stdio;
>> 	import core.stdc.errno;
>> 	import core.sys.posix.stdio;
>> 	import core.sys.posix.unistd;
>> 	
>> 	string ip;
>>
>> 	
>> 	int get(string if_name)
>> 	{
>> 		int s = socket(AF_INET, SOCK_DGRAM, 0);
>> 		if (s < 0) {
>> 			fprintf(stderr, "Create socket failed!errno=%d", errno);
>> 			return -1;
>> 		}
>> 	
>> 		ifreq ifr;
>> 		uint nIP, nNetmask, nBroadIP;
>>
>> 		strcpy(ifr.ifr_name.ptr, std.string.toStringz(if_name));
>> 		try {
>> 			if (ioctl(s, SIOCGIFHWADDR, &ifr) < 0) {
>> 				return -2;
>> 			}
>> 		}
>> 		catch (Exception e) {
>> 			writeln("Error operation on netif " ~ if_name);
>> 			return -2;
>> 		}
>> 		memcpy(macaddr.ptr, cast(char *)ifr.ifr_hwaddr.sa_data.ptr, 
>> 6);
>> 	
>> 		if (ioctl(s, SIOCGIFADDR, &ifr) < 0) {
>> 			nIP = 0;
>> 		}
>> 		else {
>> 			nIP = *cast(uint*)(&ifr.ifr_broadaddr.sa_data[2]);
>> 			ip = fromStringz(inet_ntoa(*cast(in_addr*)&nIP)).idup;
>> 		}
>>        }
>>
>> ```
>
>
>
> Gives a lot of errors when compiling
>
> ```d
> app.d(19): Error: function 
> `std.stdio.makeGlobal!"core.stdc.stdio.stderr".makeGlobal` at 
> /usr/include/dlang/dmd/std/stdio.d(5198) conflicts with 
> variable `core.stdc.stdio.stderr` at 
> /usr/include/dlang/dmd/core/stdc/stdio.d(927)
> app.d(19): Error: function 
> `core.stdc.stdio.fprintf(shared(_IO_FILE)* stream, scope 
> const(char*) format, scope const ...)` is not callable using 
> argument types `(void, string, int)`
> app.d(19):        cannot pass argument 
> `makeGlobal(StdFileHandle _iob)()` of type `void` to parameter 
> `shared(_IO_FILE)* stream`
> app.d(23): Error: undefined identifier `ifreq`
> app.d(26): Error: undefined identifier `string` in package `std`
> app.d(39): Error: undefined identifier `macaddr`
> app.d(48): Error: undefined identifier `fromStringz`
> ```

     ```d
     struct ifreq {
     	private union ifr_ifrn_ {
     		char[IFNAMSIZ] ifrn_name; /* if name, e.g. "en0" */	
     	}
     	ifr_ifrn_ ifr_ifrn;

     	private union ifr_ifru_ {
     		sockaddr ifru_addr;
     		sockaddr ifru_dstaddr;
     		sockaddr ifru_broadaddr;
     		sockaddr ifru_netmask;
     		sockaddr ifru_hwaddr;
     		short	ifru_flags;
     		int	ifru_ivalue;
     		int	ifru_mtu;
     		ifmap ifru_map;
     		byte[IFNAMSIZ] ifru_slave;	/* Just fits the size */
     		byte[IFNAMSIZ] ifru_newname;
     		byte * ifru_data;
     	}
     	ifr_ifru_ ifr_ifru;

     	// NOTE: alias will not work : alias ifr_ifrn.ifrn_name	    
ifr_name;
     	@property ref ifr_name() { return ifr_ifrn.ifrn_name; } /* 
interface name */
     	@property ref ifr_hwaddr() { return ifr_ifru.ifru_hwaddr; } 
/* MAC address */
     	@property ref ifr_addr() { return ifr_ifru.ifru_addr; } /* 
address */
     	@property ref ifr_dstaddr() { return ifr_ifru.ifru_dstaddr; 
} /* other end of p-p lnk */
     	@property ref ifr_broadaddr() { return 
ifr_ifru.ifru_broadaddr; } /* broadcast address	*/
     	@property ref ifr_netmask() { return  ifr_ifru.ifru_netmask; 
} /* interface net mask */
     	@property ref ifr_flags() { return ifr_ifru.ifru_flags; } /* 
flags	*/
     	@property ref ifr_metric() { return ifr_ifru.ifru_ivalue; } 
/* metric */
     	@property ref ifr_mtu() { return ifr_ifru.ifru_mtu; } /* mtu 
*/
     	@property ref ifr_map() { return ifr_ifru.ifru_map; } /* 
device map */
     	@property ref ifr_slave() { return ifr_ifru.ifru_slave; } /* 
slave device */
     	@property ref ifr_data() { return ifr_ifru.ifru_data; } /* 
for use by interface */
     	@property ref ifr_ifindex() { return ifr_ifru.ifru_ivalue; } 
/* interface index */
     	@property ref ifr_bandwidth() { return ifr_ifru.ifru_ivalue; 
} /* link bandwidth */
     	@property ref ifr_qlen() { return ifr_ifru.ifru_ivalue; } /* 
queue length */
     	@property ref ifr_newname() { return ifr_ifru.ifru_newname; 
} /* New name */
     }

```